The present invention relates to an optical microcantilever capable of effectively propagating light, and a manufacturing method thereof, and a microcantilever holder for fixing an optical element actuated by the optical microcantilever and light incident to the optical microcantilever, and light outputted from the optical microcantilever.
With such scanning near field microscopes, the tip of a rectilinear optical fiber probe maintained perpendicular to the sample is made to vibrate horizontally with respect to the sample surface and changes in the amplitude of vibrations occurring due to the shear force between the sample surface and the tip of the optical fiber are detected. Changes in the amplitude are detected by irradiating the tip of the optical fiber probe with laser light and detecting changes in the shadow of the tip. A gap between the tip of the optical fiber probe and the surface of the material is kept fixed by moving the sample using a fine-motion mechanism so that the amplitude of the vibrations of the optical fiber probe are constant, and the shape of the surface is detected and the optical permeability of the sample measured from the intensity of a signal inputted to the fine-motion mechanism.
There is also proposed (in Japanese Patent Publication Laid-open No. Hei. 7-17452) a scanning near field atomic force microscope where near field light is generated at the tip of an optical fiber probe as a result of introducing laser light into an optical fiber probe simultaneously with an AFM operation employing the pointed optical fiber probe as a cantilever for an atomic force microscope (hereinafter referred to as AFM) and the shape of the surface of a sample is detected and the optical characteristics of the sample are measured using the mutual interaction between the generated near field light and the sample. FIG. 12 is a side cross-section of a related example of an optical waveguide probe. This optical waveguide probe 110 employs an optical waveguide 101 as an optical fiber and the optical waveguide 101 is surrounded by a metal film 102. A pointed tip 103 is formed at one end of the optical waveguide probe 110 and a microscopic aperture 104 for generating near field light is provided at the end of the tip 103. The tip 103 is formed by bending the tip of the optical waveguide probe 110 around towards the sample (not shown).
Microcantilevers of the kind shown in FIG. 13 are well known in the related art (T. Niwa et al., Journal of Microscopy, vol. 194, pt. 2/3, pp. 388-392). At an optical microcantilever 120, an optical waveguide 11I is laminated from a core layer and a cladding layer and a metal film 112 is provided at the surface of the optical waveguide 111. A pointed tip 119 is formed at one end of the optical microcantilever 120 and a support section 114 for fixing the optical microcantilever 120 is formed at the other end of the optical microcantilever 120. A microscopic aperture 113 for generating near field light is provided at the end of the tip 119.
The end of the optical microcantilever 120 at which the tip 119 is formed is referred to as the free end of the cantilever, and the optical waveguide end where the support section 114 is formed is referred to as the incident light end 117. The free end is bent in such a manner that the microscopic aperture 113 becomes in close proximity to the sample (not shown), and light propagated from the incident light end 117 enters the optical waveguide 111.
An optical fiber guide channel 115 for fixing the optical fiber is formed at the support section 114. FIG. 14 shows the situation when an optical fiber 130 is fixed to the optical fiber guide channel 115. Light propagating from the optical fiber 130 enters the optical waveguide 111 via the incident light end 117 and is guided to the microscopic aperture 113 by the optical waveguide 111. Near field light is generated in the vicinity of the microscopic aperture 113 as a result of propagating light attempting to pass through the microscopic aperture 113. Conversely, near field light generated at the surface of the sample is scattered by the microscopic aperture 113 so as to generate propagating light and this propagating light can be detected at the incident light end 117 via the microscopic aperture 113 and the optical waveguide 111. Installation of the optical fiber 130 is straightforward because the optical fiber guide channel 115 is provided at the support section 114 and there is little trouble involved in aligning the optical microcantilever 120 and the optical fiber 130 during changing, etc.
However, productivity for the optical waveguide probe 110 is poor because the optical fiber 101 is employed as a material, which involves a large number of steps and is made manually. Further, even if the optical fiber 101 is covered in the metal film 102, propagating light loss occurs at locations where the optical fiber 101 is bent and light is therefore not propagated in an efficient manner, with this loss becoming more substantial as the angle of bending becomes more dramatic. Conversely, if the angle of bending is made smoother, the optical fiber probe becomes longer and handling therefore becomes more troublesome.
The optical microcantilever 120 has superior productivity and uniformity but loss of propagating light occurs at the optical waveguide 111 even when the metal film 112 is provided at the surface of the optical waveguide 111 and the propagating light cannot be propagated in an effective manner. In this manufacturing process, a smooth sloping surface 116 occurs between the incident light end 117 and the optical fiber guide channel 115 as shown in FIG. 14 and it is therefore difficult to get the optical fiber 130 sufficiently close to the incident light end 117 and the efficiency of the incident light is poor, i.e. coupling loss increases. Light is scattered at the incident light end 117 of the optical microcantilever 120 while light is made to pass through the incident light end 117 by the optical fiber 130 and scattered light also propagates in the direction of the microscopic aperture 113. This therefore causes the S/N ratio of a light image for the scanning type near field microscope to fall.
In order to resolve the aforementioned problems in the conventional art, it is an object of the present invention to provide an optical microcantilever bar capable of admitting and propagating light in an efficient manner, and a manufacturing method for making the optical microcantilever. It is a further object to provide an optical microcantilever holder for supporting the optical microcantilever bar and an optical element. It is a still further object to provide an optical microcantilever bar capable of improving an S/N ratio of a light image of a scanning near field microscope.
In order to achieve the aforementioned objects, an optical microcantilever according to a first embodiment of the invention is an optical microcantilever for use with a scanning near field microscope and comprises an optical waveguide, having a light input/output end and a free end, for propagating light, a tip formed at the free end, with a microscopic aperture at an end thereof, and reflecting means for reflecting light propagated from the light input/output end in such a manner that the light is guided towards the microscopic aperture, or reflecting light propagated from the microscopic aperture towards the light input/output end.
The above optical microcantilever is provided with reflecting means for reflecting light propagated from the light input/output end in such a manner that the light is guided towards the microscopic aperture, or reflecting light propagated from the microscopic aperture towards the light input/output end. This reflecting means reflects propagating light in an efficient manner and reduces loss in light propagated towards the microscopic aperture.
Further, an optical microcantilever according to a second embodiment of the invention is an optical microcantilever for use with a scanning near field microscope and comprises an optical waveguide, having a light input/output end and a free end and a nose section at an angle with respect to an optical axis of propagating light passing through the light input/output end, for propagating light, a tip formed at the free end, with a microscopic aperture an an end thereof, and reflecting means for reflecting light propagated from the light input/output end in such a manner that the light is guided towards the microscopic aperture, or reflecting light propagated from the microscopic aperture towards the light input/output end.
The above optical microcantilever is provided with reflecting means for reflecting light propagated from the light input/output end in such a manner that the light is guided towards the microscopic aperture, or reflecting light propagated from the microscopic aperture towards the light input/output end, and a portion having an angle with respect to an optical axis of propagating light passing through the light input/output end. This reflecting means reflects propagating light in an efficient manner and reduces loss in light propagated towards the microscopic aperture. It is therefore possible to observe the surface of a material having a large step by adjusting the length of the portion having an angle with respect to the optical axis of the propagating light passing through the light input/output end.
In the optical mirocantilever according to the first and second embodiments of the invention, at least part of the optical waveguide comprises a core, and a cladding is deposited on one side of the core, or both sides of the core, or is deposited so as to surround the core.
Because the optical waveguide of this optical microcantilever comprises a core, and cladding deposited on one side of the core, or both sides of the core, or deposited so as to surround the core, propagating light propagated by the optical waveguide is prevented from leaking to the outside, and the propagating light is propagated within the optical waveguide under conditions of total reflection.
In the optical microcantilever according to the foregoing embodiments, a light-blocking film is provided on the optical waveguide at the side where the tip is formed, and a reflecting film is provided at the opposite side to the side where the tip is formed.
As a result of providing this optical microcantilever with a light-blocking film on the optical waveguide at the side where the tip is formed, and a reflecting film at the opposite side to the side where the tip is formed, propagating light propagated by the optical waveguide is prevented from leaking to the outside.
In order to achieve the aforementioned objects, a method, according to a first embodiment, of manufacturing an optical microcantilever is a method for manufacturing an optical microcantilever for use with a scanning near field microscope and includes the steps of forming a step to be taken as a mold for an optical waveguide at the substrate, depositing a reflecting film on the substrate, depositing an optical waveguide on the reflecting film, forming a tip by working the optical waveguide, depositing a light-blocking film on the optical waveguide, forming a microscopic aperture at the end of the tip, and forming a supporting section by having the substrate remain on the side to be a light input/output end and removing the substrate on the side to be the free end.
This method of manufacturing an optical microcantilever includes the steps of forming a step to be taken as a mold for an optical waveguide at the substrate, depositing a reflecting film on the substrate, depositing an optical waveguide on the reflecting film, forming a tip by working the optical waveguide, depositing a light-blocking film on the optical waveguide, forming a microscopic aperture at the end of the tip, and forming a supporting section by having the substrate remain on the side to be a light input/output end and removing the substrate on the side to be the free end.
The above optical microcantilever is provided with a reflecting film for reflecting light propagated from the light input/output end in such a manner that the light is guided towards the microscopic aperture, and reflecting light propagated from the microscopic aperture towards the light input/output end so that propagating light can be reflected in an efficient manner and loss of propagating light can be reduced. Further, batch processing is possible for these processes by employing silicon processing, and optical microcantilevers with superior productivity and uniformity can therefore be made.
In the method of the first embodiment for manufacturing the optical microcantilever, an angle of the step formed is an angle enabling propagating light propagating from the light input/output end to be guided towards the microscopic aperture by the reflecting film deposited in the reflecting film depositing step, or is an angle enabling propagating light propagating from the microscopic aperture to be guided towards the light input/output end.
In this method for manufacturing the optical microcantilever, the angle of the step formed in the step forming step is an angle that enables propagating light propagating from the light input/output end to be guided towards the microscopic aperture by the reflecting film deposited in the reflecting film depositing step, or is an angle that enables propagating light propagating from the microscopic aperture to be guided towards the light input/output end. The reflecting film formed in this manner reflects propagating light in an efficient manner and reduces loss of propagating light.
In order to achieve the aforementioned objects, an optical microcantilever according to a third embodiment of the invention is an optical microcantilever comprising a cantilever constituted by an optical waveguide, a supporting section for the cantilever, th optical waveguide having a light input/output end and a free end, an optical element guide formed at the supporting section for deciding a position of an optical element acting on light entering the optical waveguide, and a channel provided between the light input/output end and the optical element guide.
This optical microcantilever has a channel formed between the light input/output end of the optical waveguide and the optical element guide. By forming a channel between the light input/output end of the optical waveguide and the optical element guide, an inclined surface providing an obstacle between an optical element acting on light entering the light input/output end and the optical waveguide or light outputted from the optical waveguide can be made substantially perpendicular and the optical element can therefore be located close to the light input/output end.
In order to achieve the aforementioned objects, a method, according to a second embodiment, of manufacturing an optical microcantilever is a method for manufacturing an optical microcantilever for use with a scanning near field microscope, comprising the steps of forming a step to be taken as a mold for an optical waveguide at the substrate, forming an optical element guide at the substrate, depositing an optical waveguide on the substrate, forming a light input/output end of the optical waveguide, forming a channel by working the substrate between the light input/output end and the optical element guide, exposing the optical element guide by removing the optical waveguide on the optical element guide, and forming a supporting section by having the substrate remain on the side to be a light input/output and and removing the substrate on the side to be the free end.
This method of manufacturing an optical microcantilever includes the steps of forming a step to be taken as a mold for an optical waveguide at the substrate, forming an optical element guide at the substrate, depositing an optical waveguide on the substrate, forming a light input/output end of the optical waveguide, forming a channel by working the substrate between the light input/output end and the optical element guide, exposing the optical element guide by removing the optical waveguide on the optical element guide, and forming a supporting section by having the substrate remain on the side to be a light input/output end and removing the substrate on the side to be the free end.
A guide for fixing an optical element acting on light entering the light input/output end and the optical waveguide or light outputted from the optical waveguide can therefore be formed and an inclined surface providing an obstacle between the light input/output end and the optical element can be made substantially perpendicular. Further, batch processing is possible for these processes by employing silicon processing, and optical microcantilevers with superior productivity and uniformity can therefore be made.
In order to achieve the aforementioned objects, a method, according to a third embodiment, of manufacturing an optical microcantilever is a method for manufacturing an optical microcantilever for use with a scanning near field microscope, including the steps of forming a step to be taken as a mold for an optical waveguide at the substrate, forming an optical element guide at the substrate, depositing a reflecting film on the substrate, depositing an optical waveguide on the reflecting film, forming a tip by working the optical waveguide, depositing a light-blocking film on the optical waveguide, forming a microscopic aperture at the end of the tip, forming a light input/output end of the optical waveguide by removing the light blocking film, the optical waveguide, and the reflecting film, for the portion to constitute the light input/output end of the optical waveguide, forming a channel by working the substrate between the light input/output end and the optical element guide, exposing the optical element guide by removing the light-blocking film, the optical waveguide, and the reflecting film on the optical element guide, and forming a supporting section by having the substrate remain on the side to be a light input/output end and removing the substrate on the side to be the free end.
This method of manufacturing an optical microcantilever includes the steps of forming a step to be taken as a mold for an optical waveguide at the substrate, forming an optical element guide at the substrate, depositing a reflecting film on the substrate, depositing an optical waveguide on the reflecting film, forming a tip by working the optical waveguide, depositing a light-blocking film on the optical waveguide, forming a microscopic aperture at the end of the tip, forming a light input/output end of the optical waveguide by removing the light-blocking film, the optical waveguide, and the reflecting film, for the portion to constitute the light input/output end of the optical waveguide, forming a channel by working the substrate between the light input/output end and the optical element guide, exposing the optical element guide by removing the light-blocking film, the optical waveguide, and the reflecting film on the optical element guide, and forming a supporting section by having the substrate remain on the side to be a light input/output end and removing the substrate on the side to be the free end.
As a result, a guide for fixing the optical element can be formed and an inclined surface providing an obstacle between the light input/output end and the optical element can be made substantially perpendicular. Further, a reflecting film for reflecting light propagated from the light input/output end in such a manner that the light is guided towards the microscopic aperture, or reflecting light propagated from the microscopic aperture towards the light input/output end can be formed, propagating light can be reflected in ant efficient manner, and there is no longer any loss of propagating light. Further, batch processing is possible for these processes by employing silicon processing, and optical microcantilevers with superior productivity and uniformity can therefore be made.
In order to achieve the aforementioned objects, there is also provided an optical microcantilever guide for supporting an optical microcantilever, and an optical element guide for deciding a position of an optical element acting on light entering the optical microcantilever or on light exiting from the optical microcantilever.
With this optical microcantilever holder, an optical microcantilever guide for supporting an optical microcantilever and an optical element guide for supporting the optical element at the optical microcantilever are formed. The optical microcantilever and the optical element can therefore be aligned simply by installing the optical microcantilever at the optical microcantilever guide and installing the optical element at the optical element guide.
In order to achieve the aforementioned objections, an optical microcantilever according to a fourth embodiment is an optical microcantilever comprising a cantilever-shaped optical waveguide, a tip formed at the free end of the optical waveguide and having a microscopic aperture at an end, thereof, wherein the optical waveguide comprises: a light input/output end at a fixed end thereof, a nose section formed between the free end and the fixed end at an angle with respect to an optical axis of the optical waveguide of the fixed end, and reflecting means for reflecting light propagating from the light input/output end in such a manner that the light is guided towards the nose section, and/or reflecting light detected by the microscopic aperture and transmitted to the nose section towards the light input/output end.
Further, in the optical microcantilever of the fourth embodiment, the optical waveguide has a head section at the end of the nose section extending substantially parallel with the optical waveguide of the fixed end, and the tip is formed at the head section.
This optical microcantilever can measure samples with large steps as a result of the nose section being provided, and the tip is easy to form.
In order to achieve the aforementioned objects, the optical microcantilever according to any of the foregoing embodiments has a lens provided between the tip and the reflecting means. Preferably, the lens is a convex lens. Alternatively, the lens is a fresenel lens. Still further, the lens is preferably a gradient-index lens.
Further, the light of a high energy density can be guided into the microscopic aperture using the lens and near field light irradiated from the microscopic aperture can be of a substantial intensity. And/or, light detected by the microscopic aperture can be transmitted to a detector in an efficient manner as detection light by collimating the detected light using the lens.
In order to achieve the aforementioned objects, in the optical microcantilever according to any of the foregoing embodiments, the tip of the optical microcantilever employed in a scanning near field microscope is formed of a material having a higher refractive index that the optical waveguide.
Because the tip of this optical microcantilever is formed of a material of a high refractive index, efficiency of irradiation of light from the microscopic aperture and/or the efficiency of generation of near field light to be detected and/or the efficiency of detection can be: increased.
In order to achieve the aforementioned objects, an optical microcantilever according to a fifth embodiment comprises a substrate, a cantilever-shaped optical waveguide formed at the substrate, a tip, having a microscopic aperture at an end thereof, formed at a side of the free end of the cantilever, a light input/output end positioned at a side of the fixed end of the optical waveguide, and an optical element guide, formed on the substrate on the side of the light input/output end, for deciding a position of an optical element acting on light entering the optical waveguide and on light exiting from the optical waveguide, wherein the light input/output end projects above the optical element guide.
With this optical microcantilever, a distance between the light input/output end and the optical element can be made shorter because the light input/output end projects above the optical element guide. The efficiency with which light entering the optical waveguide and/or light outputted from the optical waveguide can be introduced and/or detected is therefore good.
In order to achieve the aforementioned objects, an optical microcantilever according to a sixth embodiment comprises a substrate, a cantilever-shaped optical formed at the substrate, a light input/output end positioned at a side of the fixed end of the optical waveguide, a tip provided at the side of the free end of the cantilever and having a microscopic aperture at an end thereof, and light-blocking means for ensuring that light scattered by the light input/output end is not transmitted in the direction of the tip.
Further, in the optical microcantilever of the sixth embodiment, the light-blocking means is arranged above the substrate and the optical waveguide, and provides a wall for blocking the scattered light.
Further, in the optical microcantilever of the sixth embodiment, the light-blocking means comprises a light-blocking agent located on the substrate an the optical waveguide and a light-blocking film located on the light-blocking agent, and the light-blocking film is located in such a manner as to cover at least the light in light input/output end.
Further, in the optical microcantilever of the sixth embodiment, the light-blocking means comprises a light-blocking film located on the substrate and the optical waveguide and a light-blocking agent arranged so as to cover at least part of an end of the light-blocking film, and the light-blocking film is located in such a manner as to cover at least the light input/output end. Preferably, the light-blocking film is movable.
With this optical microcantilever, the light-blocking means ensures that light scattered by the light input/output end is not transmitted in the direction of the tip and this therefore improves the S/N ratio of optical images of the scanning near field microscope so that the scanning speed of the scanning near field microscope can be improved accordingly. Deciding of the position of the optical element and the light input/output end of the waveguide can be performed during observation because the light-blocking film is movable and positioning of the optical element can therefore be carried out in a precise and straightforward manner: